- One of Vitamin B12's major functions is to make DNA for new cell growth.
- Despite what some supplements promise, it won’t boost your energy if you’re not deficient
- If you’re a vegan, studies have confirmed that you’re likely to be deficient in B12.
From our blood cells to our nerves to our very DNA, Vitamin B12 is a critical vitamin for our bodies. It’s so important, in fact, that our stomachs have developed special receptors for it. But there’s a lot of confusion about this important nutrient. For example, B12 deficiency is not obvious, and some of its symptoms are irreversible (nerve damage for example). On the flip side, despite what some supplements promise, it won’t boost your energy if you’re not deficient.
Why do we need B12? What does it do in the body?
Humans need Vitamin B12 for life - it is absolutely essential. Vitamin B12 is actually a series of very closely related, rather complicated molecules. One of its major functions is to make DNA for new cell growth (no new DNA translates to no new cells, including blood cells). B12 shortages are not always obvious, and can have damaging effects. Coupled with less energy and physical stamina, you can see why skimping on this vitamin can really affect your health.
Is there a form that’s best? What should we be looking for on labels?
We prefer methylcobalamin (MeB12). It’s the form of B12 you’d find the most of in our bodies and in foods. However, supplements and fortified foods tend to use a different form - cyanocobalamin - because it has a longer shelf life than methylcobalamin. Our bodies need to convert cyanocobalamin to MeB12, but there are potential problems with conversions. Cyanocobalamin also contains a cyanide molecule instead of a methyl one, but the amount of cyanide in cyanocobalamin is tiny and far less than what we get from healthy foods. So despite what you might read on the web, it is not a safety concern.
What are the symptoms of B12 deficiency?
Tiredness, fatigue, weakness, constipation, numbness or tingling hands and feet, balance issues, forgetfulness, confusion and sad/grouchy mood are all possible signs that you need more B12.
What foods contain B12?
If you’re a non-vegan, you can get it from animal foods - meats, dairy and eggs. Vegetarians and vegans have a harder time. Nori and dulse seaweeds are the only viable sources of B12 for strict vegans, and you'd need to eat a lot. Other algae (like spirulina), seaweeds and certain kinds of mushrooms have pseudo-B12, which does not work in the human body.
So if you’re vegetarian or vegan, how hard is it to meet your Daily Value?
If you’re a strict vegan, be aware that studies have confirmed that you’re likely to be deficient in B12, unless you’re taking supplements with B12. If you’re just a non-meat eater, then you have a better chance of getting enough, but many studies show that even then it can be tough. Food fortification has helped somewhat (you mostly get it in bread and grains).
Do vegans need a B complex or will B12 alone suffice?
In general, B12 alone is good enough because most plant foods have plenty of the other B vitamins (though vitamin B6 can also sometimes be a problem).
Are there any other populations who need more? Or health conditions that might cause a deficiency?
According to the National Institutes of Health Office of Dietary Supplements, there are several groups that need to pay attention to getting plenty of B12: older adults, anyone with less stomach acid (including taking OTC drugs that block stomach acid), and anyone with gastrointestinal conditions that hamper absorption.
Can you get too much?
No - B12 has been shown to be safe even from massive injectable doses or oral megadoses. It does have cobalt, but the amount is so small that you’d have to eats handfuls of pure B12 and not much else to even get close to cobalt toxicity. If you ingest excess B12, your body simply does not absorb it - your body will get rid of it.